The overall purpose of this research proposal is to examine the role of the limbic system in hypothalamic aggression. The first phase of the research project attempts to determine how the limbic system and related cortical structures modulate attack behavior elicited by electrical stimulation of the hypothalamus. The principal paradigm involves presentation of paired trials of single (hypothalamic) and dual (limbic plus hypothalamic) stimulation. Differences in response latency between paired trials of single and dual stimulation provide the basis for determining the effects of limbic stimulation upon hypothalamic attack behavior. The limbic structures thus far studied include the hippocampus, septal area, cingulate gyrus and pyriform cortex. Other structures to be studied include cortical areas anatomically related to the limbic system. A second phase of this project will attempt to determine the neuroanatomical projections of those structures producing modulating effects upon attack behavior. The third phase will attempt to determine the neurophysiological relationships between those structures producing modulating effects upon attack behavior and their target nuclei as determined by neuroanatomical methods.